CHEAPEST way to go digital HELP NEEDED

Licence free two-way radio services that now includes both FM and digital channels. Discuss models, modifications and other similar worldwide standards such as FRS and GMRS.
paulears
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Re: CHEAPEST way to go digital HELP NEEDED

Postby paulears » 03 Jan 2017, 17:31

I guess we just need to wait until somebody does some proper tests with the right test gear to find out what is happening.

We have similar issues with some of the Chinese lighting equipment I use when they deviate slightly from the DMX protocol, and unusual and quite weird things happen for no apparent reason - in most cases it's timing accuracy for the packets. Some of these needed replacement chips to cure the problem, but a few were sorted with firmware revisions. Not sure if it was ever tracked down to poor coding, or proper instability - I doubt Baofeng will be very transparent on this one.

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radiosification
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Re: CHEAPEST way to go digital HELP NEEDED

Postby radiosification » 05 Jan 2017, 17:10

paulears wrote:Take the point on dPMR, but radar with high PRR has been around for a long time, so certainly possible to switch extremely fast nowadays.

I guess you're referring to being able to switch on and off the PA fast enough here for TDMA. It's possible yes, but it's probably not cheap to do and I think that's why the decided to leave it out of these certain DMR radios.
paulears wrote:So do all DMR portables sync themselves to incoming RF? This suggests that repeaters need to be transmitting continuously, or at least regularly. So each radio sync up with the incoming data ready for TX in the right time slot. I used the term format to refer to the data packet format - bursts and frames. I'm familiar with the format of data streams. In DMR the guard bands are very small as a percentage of the total time for each packet - not surprising clashes happen.

So is the problem really sloppy timing or something more complicated. Sync lockup could be a firmware tweak, hopefully.

They do sync to the repeater before transmitting, yes. Essentially what happens is if a radio user wants to talk the radio will listen to the repeater first to get the correct timing to transmit in the slot it's programmed to. If the repeater is not transmitting already, the radio will ping it to get it to transmit and then it will sync up before transmitting voice.

The problem with these radios is not timing at all. It's just that the PA doesn't turn on and off fast enough. Basically if they tried to turn the PA off for the other timeslot it would still be mostly on by the time the radio wanted to transmit again in its own timeslot. Which means it is transmitting over the other timeslot and blocking it. I guess instead of attempting and failing to turn it off between transmitting in a timeslot, they decided to just leave it on. It could only be solved by rebuilding the radio with a better PA and then modifying the firmware to get it to turn the PA on and off. Not something the consumer could really do, and not something the manufacturer will do either. The best option is just to buy a different radio in the first place.
If you're interested in digital, check out my YouTube channel:
http://www.youtube.com/radiosification

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Re: CHEAPEST way to go digital HELP NEEDED

Postby paulears » 06 Jan 2017, 18:45

That's useful, thanks - it does seem that building on a design flaw is never going to be a possible modification if the entire transmit chain is incapable of doing this, and just idling in the 'wrong' data slot. I wonder if they simply use the same PA module that FDMA radios use? Kenwood have been trying to sell me some of their NXDN kit that has been tweaked to operate on dPMR too, but they won't confirm that both formats are able to be used in different channels. Their advertising is a bit blurry in places.

It will be interesting to see if this baofeng radio ever gets sold in a Tier II capable form, won't it?

Thanks
Paul

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Re: CHEAPEST way to go digital HELP NEEDED

Postby troffasky » 06 Jan 2017, 22:16

Looks like it's based on hr_c3000f DMR chip:

http://www.hamradio.cc/forum/index.php?t=msg&goto=3232
[note the AT1846S for the analogue side, presumably a clone of the RDA1846S]

Very little on Google about this, however Baidu yields more hits:

http://www.baidu.com/s?wd=hr-c3000f%20dmr

and we find this:

http://www.qy6.com/qyml/showp13175880.html
[you'll have to stick it into Google Translate]

which is a company selling modules based around DMR ICs. Now obviously it may lose something in translation, but what I read from that page is that the basic model they sell uses the HR_C3000 and the more advanced one uses the HR_C5000. A quick Google for "HR_C5000" shows that it's used in the MD-380! Note that on the qy6 link, the blurb for the advanced module specifically mentions TDMA, but the blurb for the basic one does not.

Nothing on the manufacturer's site about C5000, only C3000:

http://www.hongruitech.com.cn/index.php ... /cid/8/s/3

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Re: CHEAPEST way to go digital HELP NEEDED

Postby Farty » 07 Jan 2017, 11:49

WARLOCK wrote:Is there a cheap way to get onto digital radio ,these days ???


Yes, join the police and get given one.

Or steal one.

Neither is really recommended though.
In Before The Lock Champion of Total Awesomeness May 2016

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radiosification
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Re: CHEAPEST way to go digital HELP NEEDED

Postby radiosification » 07 Jan 2017, 22:08

paulears wrote:It will be interesting to see if this baofeng radio ever gets sold in a Tier II capable form, won't it?

It already is (mis)sold as a tier 2 radio. Check out the DM-5R plus

Farty wrote:
WARLOCK wrote:Is there a cheap way to get onto digital radio ,these days ???


Yes, join the police and get given one.

That isn't cheap at all. You have to do a degree to get in these days!

Troffasky, some good info there!
If you're interested in digital, check out my YouTube channel:
http://www.youtube.com/radiosification

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Re: CHEAPEST way to go digital HELP NEEDED

Postby Admiral » 08 Jan 2017, 08:37

It was always anticipated that after a couple of years and the R&D and tooling costs were covered that the price of an MD380/RT3 would settle at around £59 retail. That's still a few months away, currently they can be had for £75 with cable.

http://www.ebay.co.uk/itm/like/36162438 ... 085&crdt=0

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gmham
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Re: CHEAPEST way to go digital HELP NEEDED

Postby gmham » 08 Jan 2017, 10:59

£55 for the zastone D900 clone before Xmas on amazon so yes they certainly are coming down in price. Even at the current £75 I still think they are a good buy . the build quality seems very good indeed.
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